100 OBSERVATIONS ON NAIADES, 



terior wing recurved at top; beaks slightly prominent; ligament con- 

 cealed in the vv^ing ; epidermis brown, with obsolete rays ; two or three 

 fuscous lines pass from the beak to the posterior margin above the um- 

 bonial slope ; cardinal tooth single in both valves, and lamelliform ; 

 lateral teeth bladed and elevated towards their termination ; the two 

 teeth form one continuous curve line (with the exception of a slight 

 angle where they join) which is abrupt at both ends ; anterior cicatri- 

 ces distinct ; posterior cicatrices confluent ; dorsal cicatrices pass from 

 the cavity towards the anterior cicatrices, and are very perceptible ; 

 cavity of the beaks wide and shallow ; nacre purple and iridescent. 



Remarks. — I am indebted, for this fine shell, to Judge Tait of Ala- 

 bama, who kindly sent it to me with several other new species of fluvi- 

 atile and terrestrial shells described in this paper. This species seems to 

 form*a natural link between S. Isevissima (Nob.) and S. bialata (Nob.). 

 It resembles the former in colour and in the teeth, but differs in the 

 elevation of the wing, and in being less shining and more ventricose. It 

 resembles the latter in its elevated wing and general outline, but dif- 

 fers from it in nacre, exterior colour, in not being possessed of undu- 

 lations along the base of the posterior wing, and in the teeth. 



Melania Subularis. Plate XV. fig. 30. 



Testa elevata, turritd, cornea; apice acuta; anfractibus inslar duodenis, planis; 

 anfractu infimo in medio carinato; aperturd alba, quadrante longitudinis testa. 



Shell elevated and acutely turrited, horn colour ; apex acute ; whirls about twelve, 

 flat, carinate on the middle of the body whirl ; base angulated ; aperture white and 

 one-fourth the length of the shell. 



Hab. Niagara river. 



My Cabinet. 

 Diam. -4, Length 1*3 inches. 



Remarks. — I took this species at the Falls of Niagara, and being un- 



